RS34 Flow Test

larrycavan wrote:

kzz1p wrote:

:laugh:

Hey Larry,

Out of that 30fps lost. Could any of that be recovered by running an intake cam, with a fatter duration then the exhaust?

Excellent question No easy answer unfortunately.

For those few brief degrees of overlap, intake velocity will get that supercharge effect. But the catch is trapping the charge in the cylinder.

Look at what's happening during that period. Valve lifts are going to be relative to cam profile and timing. There's going to be waste out the exhaust to some extent.

It's another example of the upside / downside of poppet valve 4 cycle engines. Get some here...loose some there.

Some head porters will intentionally try to kill off low lift flow to fight charge loss. In some cases good low lift flow can have the affect of adding duration to the cam....

Is the charge lost out the exhaust btdc or after?
Btdc, is the air speed ahead of the piston faster than the exhaust air exiting the port? Do the speeds change with increase of rpm? If charge is lost atdc, why would one want to keep the exhaust open open any longer? Reason I ask these q's is my exhaust closes earlier than the cam spec declare, high end power seems pretty good. If I can tune the timing for max velocity for supercharge at high rpm I'll set it up that way. I want the fastest best mixing charge I can have, at the highest rpm that suits my favor. People have been talking about the timing events of a camshaft forever but they always have only part of the information. To me it either runs better or worse. But one has to start adjusting something right? What is the advantage of saving a little fuel from escaping? Is it bad for the converter? I figure that the most charge is the best and screw the rest. All I want is to know the system and make the best of it tuning it the way I would like it to operate. Hard to do without the vision, ya know. Gota understand it to be able to work with it. All I know is the intake closes early, the engine stops making power, I don't care how much it has already made. If that power comes from velocity, the velocity must not drop, the charge must not stop.

TeK9iNe wrote:

Careful.... I hear post like that are "just wack"